Current state-of-the art postal letter mail equipment is divided into two types, those that primarily process addresses, and those that process mail that has been bar coded. Bar code processing equipment is simpler in design and does not require as long a transport belt path because the time to process a mail piece image is less for one containing a bar code than one containing only address information. Bar codes typically included on mail items are traditional linear bar code types as well as two dimensional code patterns that contain alphanumeric and ZIP code data.
Many efforts to improve bar code recognition have been employed to increase the effective yield of the machines to as high as 90%, but ultimately severely degraded images, or those wherein the bar code is obscured by an envelope's window edge, cause a certain percentage of mail items to be rejected. Mail items with bar codes that cannot be read are rejected and either processed manually or reprocessed on other equipment capable of reading the full address. These later steps result in additional costs and delay in processing the mail items, and depending upon the specific step of the production process, this can sometimes result in an extra day to deliver the item.
Some bar-coded mail items have an additional identification code used to associate an image with the mail item. These pieces had been previously processed and a sorting bar code applied by an OCR sorting system as deployed by the USPS, or by a mail processing companies that have equipment similar to the USPS and who are operating under license to the USPS. The ID code is read by a separate bar code reader and is used by the bar code sorters to enable each to query a central server for bar code equivalent data when sorting bar codes cannot be read. The server receives the bar code equivalent data, i.e., data from which a correct destination bar code for that mail piece can be determined, from a process such as video coding. A need persists for a system able to provide a higher read success rate for bar code sorters.